The present invention relates to a measuring station for a photometer. The term "photometer" refers to light measuring apparatus in general and includes photometers using light absorption, light diffusion, liquid scintillation, luminescence or the like. Photometers using luminescence are sometimes referred to as luminometers.
One known measuring station for a photometer has a hollow measuring chamber into which a sample is introduced through an aperture by means of a plunger. Such a measuring chamber may be used, for example, for the uses described in German Offenlegungschrift No. 29 01 919, and corresponding U.S. Pat. No. 4,390,274.
In measuring stations in which a plunger lifts the sample or a sample vessel containing a sample to be measured into the measuring chamber, the plunger has to have a smaller cross section than the aperture through which the sample or sample vessel passes into the measuring chamber. This raises the problem of sealing the plunger to the walls of the aperture in order to prevent light ingress into the measuring chamber which would otherwise ruin the measurement. It would be possible to seal the plunger to the measuring chamber by means of a sealing element in the form of a multiple-leaf diaphragm located in the aperture, the diaphragm closing around the plunger when the sample has been introduced into the measuring chamber. However, such an arrangement would be complex and expensive.